(1) Field of the Invention
The present invention relates to a high-strength golf ball.
(2) Description of the Related Art
Heretofore, golf balls comprising a butadiene rubber core and an ionomer resin cover have been the main type as two-piece solid golf balls. A golf ball having an ionomer resin cover exhibits a long carry or flight distance and great durability; however, the hitting impact feels hard, and because contact time of the ball with a club head is short, it tends to lower ball control.
Therefore, in recent years, to achieve a soft-feeling when hit and improve ball control, multi-piece solid golf balls wherein an interlayer of soft material is provided between the core and the cover, or wherein the cover is formed of a soft material, have also been used.
The properties required in golf balls include a soft-feeling on impact, controllability, and a long flight distance. When soft materials are used for each layer, the soft-feeling on impact can be obtained but the carry distance is reduced. In contrast, when hard materials are used, the flight distance increases but the hitting impact feels hard. Therefore, it is difficult to attain a golf ball that provides these incompatible properties in the same ball.
Furthermore, golf balls must have sufficient durability to withstand intense striking. For example, cracking that is generated in a ball when hit may instantaneously spread, splitting the ball. In particular, with an Iron, the surface of the cover of the ball may become nappy or scratched, or some dimples may be scraped off. To prevent the spread of cracking and/or damage to the surface, materials having a high tensile strength and elongation at break, or hard materials, may be used, but due to the increased elastic modulus, these balls have a hard-feeling on impact and/or a reduced carry distance.